Find research datasets worth reusing

Data from: Assortative mating by flowering time and its effect on correlated traits in variable environments

Reproductive timing is a key life history trait that impacts the pool of available mates, the environment experienced during flowering, and the expression of other traits through genetic covariation. Selection on phenology, and its consequences on other life history traits, has considerable implications in the context of ongoing climate change and shifting growing seasons. To test this, we grew field-collected seed from the wildflower Mimulus guttatus in a greenhouse to assess the standing genetic variation for flowering time and covariation with other traits. We then created full-sib families through phenological assortative mating and grew offspring in three photoperiod treatments representing seasonal variation in daylength. We find substantial quantitative genetic variation for the onset of flowering time, which covaried with vegetative traits. In the assortatively-mated offspring, we discover over 2-hours variation in critical photoperiod, so that families differed in the probability of flowering across treatments. Allocation to flowering and vegetative growth changed across the daylength treatments, with consistent direction and magnitude of covariation amongst flowering time and other traits. Our results suggest that future studies of flowering time evolution should consider the joint evolution of correlated traits and shifting seasonal selection to understand how environmental variation influences life histories.

opencc-zeroDec 2013View details →

Data from: Establishing macroecological trait datasets: digitalization, extrapolation, and validation of diet preferences in terrestrial mammals worldwide

Ecological trait data are essential for understanding the broad-scale distribution of biodiversity and its response to global change. For animals, diet represents a fundamental aspect of species' evolutionary adaptations, ecological and functional roles, and trophic interactions. However, the importance of diet for macroevolutionary and macroecological dynamics remains little explored, partly because of the lack of comprehensive trait datasets. We compiled and evaluated a comprehensive global dataset of diet preferences of mammals ("MammalDIET"). Diet information was digitized from two global and cladewide data sources and errors of data entry by multiple data recorders were assessed. We then developed a hierarchical extrapolation procedure to fill-in diet information for species with missing information. Missing data were extrapolated with information from other taxonomic levels (genus, other species within the same genus, or family) and this extrapolation was subsequently validated both internally (with a jack-knife approach applied to the compiled species-level diet data) and externally (using independent species-level diet information from a comprehensive continentwide data source). Finally, we grouped mammal species into trophic levels and dietary guilds, and their species richness as well as their proportion of total richness were mapped at a global scale for those diet categories with good validation results. The success rate of correctly digitizing data was 94%, indicating that the consistency in data entry among multiple recorders was high. Data sources provided species-level diet information for a total of 2033 species (38% of all 5364 terrestrial mammal species, based on the IUCN taxonomy). For the remaining 3331 species, diet information was mostly extrapolated from genus-level diet information (48% of all terrestrial mammal species), and only rarely from other species within the same genus (6%) or from family level (8%). Internal and external validation showed that: (1) extrapolations were most reliable for primary food items; (2) several diet categories ("Animal," "Mammal," "Invertebrate," "Plant," "Seed," "Fruit," and "Leaf") had high proportions of correctly predicted diet ranks; and (3) the potential of correctly extrapolating specific diet categories varied both within and among clades. Global maps of species richness and proportion showed congruence among trophic levels, but also substantial discrepancies between dietary guilds. MammalDIET provides a comprehensive, unique and freely available dataset on diet preferences for all terrestrial mammals worldwide. It enables broad-scale analyses for specific trophic levels and dietary guilds, and a first assessment of trait conservatism in mammalian diet preferences at a global scale. The digitalization, extrapolation and validation procedures could be transferable to other trait data and taxa.

Data from: An inversion supergene in Drosophila underpins latitudinal clines in survival traits

Chromosomal inversions often contribute to local adaptation across latitudinal clines, but the underlying selective mechanisms remain poorly understood. We and others have previously shown that a clinal inversion polymorphism in Drosophila melanogaster, In(3R)Payne, underpins body size clines along the North American and Australian east coasts. Here we ask whether this polymorphism also contributes to clinal variation in other fitness-related traits, namely survival traits (lifespan, survival upon starvation, and survival upon cold shock). We generated homokaryon lines, either carrying the inverted or standard chromosomal arrangement, isolated from populations approximating the endpoints of the North American cline (Florida, Maine), and phenotyped the flies at two growth temperatures (18°C, 25°C). Across both temperatures, high-latitude flies from Maine lived longer and were more stress resistant than low-latitude flies from Florida, as previously observed. Interestingly, we find that this latitudinal pattern is partly explained by the clinal distribution of the In(3R)P polymorphism, which is at ~50% frequency in Florida but absent in Maine: inverted karyotypes tended to be shorter-lived and less stress resistant than uninverted karyotypes. We also detected an interaction between karyotype and temperature on survival traits. Since In(3R)P influences body size and multiple survival traits, it can be viewed as a 'supergene', a cluster of tightly linked loci affecting multiple complex phenotypes. We conjecture that the inversion cline is maintained by fitness trade-offs and balancing selection across geography; elucidating the mechanisms whereby this inversion affects alternative, locally adapted phenotypes across the cline is an important task for future work.

Data from: Introducing resprouters to enhance Mediterranean forest resilience: importance of functional traits to select species according to a gradient of pine density

Resprouter species are important for Mediterranean ecosystem resilience, but they are scarce in landscapes dominated by pioneer pines. Sound knowledge of resprouter seedling functional responses and establishment success across different pine habitats would help guide forest restoration efforts. Four broadleaved resprouter species, that is two shrubs – Arbutus unedo and Pistacia terebinthus – and two trees – Fraxinus ornus and Sorbus domestica – were planted under an experimentally created gradient of pine cover from totally open conditions to dense pine cover. Seedling survival and growth were monitored for 5 years. Phenological, physiological and morphological traits were measured to gain insight into the mechanisms of pine–seedling interaction. Interaction outcomes varied according to species identity, pine cover treatment and time. Light-to-moderate pine cover induced greater height growth and little or no effects on diameter and survival of the two trees. Competition was always detected for shrubs, whereas competition and facilitation were noted for trees. Within pine stands, negative interactions increased with tree cover, making dense stands the most limiting. Interactions were only detectable after 2–3 years, but increased in intensity with time. Functional responses to increasing pine cover indicated a seedling strategy of carbon gain optimization in the shade (increased specific leaf area and leaf area, decreased leaf dry matter content), particularly in tree species seedlings. Increasing pine cover induced higher water stress, but lower photochemical stress. The deciduous species had a longer vegetation season under pine canopies, whereas the evergreen shrub Arbutus unedo showed a lower polycyclism rate and flower production. Synthesis and applications. Moderate pine cover facilitates the establishment of deciduous trees at the expense of shrubs. This pattern can be attributed to a higher shade tolerance of the trees than the shrubs combined with a low tolerance of trees to photoinhibition. We therefore recommend using evergreen shrubs for the restoration of open land and high-specific-leaf-area deciduous trees for pine stand diversification. However, in dense forests, thinning is needed to increase light availability prior to seedling introduction.

Data from: Multi-dimensional patterns of variation in root traits among coexisting herbaceous species in temperate steppes

1. Characterizing patterns of variation in plant traits across species and environmental gradients is critical for understanding performance of species in ecosystems. One-dimensional pattern of variation has been demonstrated in leaf traits, which is known as the leaf economic spectrum. However, it is unclear whether such a spectrum exists for root traits. 2. For roots of 15 species from temperate grasslands, we determined respiration rate, relative growth rate, lifespan as well as 10 morphological, chemical and anatomical root traits. We further evaluated pairwise and multiple-trait relationships by the Pearson's correlation and principle component analysis including phylogenetic contrasts. 3. We found that root functions were related to three clusters of variation. Root respiration rate and relative growth rate were positively correlated with average root diameter, but they were negatively correlated with specific root length. In contrast, root lifespan was not correlated with average root diameter, but it was positively correlated with specific root length. These results are inconsistent with the presumption of the root economic spectrum. 4. The principle components analysis revealed a multi-dimensional pattern of variation in root traits among the 15 coexisting herbaceous species. Moreover, species within the same phylogenetic clades tended to have similar root trait syndromes. Most of the root traits exhibited a significant phylogenetic signal. 5. Synthesis. Our results do not support a one-dimensional root economic spectrum in the coexisting herbaceous species of temperate grasslands. In contrast, the pattern of variation in root traits was multi-dimensional. We further demonstrated that species in different phylogenetic clades possess diverse root trait syndromes for efficient resource acquisition. Our findings provide a next step in understanding root functions and plant strategies in temperate grasslands.

opencc-zeroDec 2016View details →

Data from: Frugivory-related traits promote speciation of tropical palms

Animal-mediated seed dispersal by frugivorous birds and mammals is central to the ecology and functioning of ecosystems, but whether and how frugivory-related traits have affected plant speciation remains little explored. Fruit size is directly linked to plant dispersal capacity and therefore influences gene flow and genetic divergence of plant populations. Using a global species-level phylogeny with comprehensive data on fruit sizes and plant species distributions, we test whether fruit size has affected speciation rates of palms (Arecaceae), a plant family characteristic of tropical rainforests. Globally, the results reveal that palms with small fruit sizes have increased speciation rates compared with those with large (megafaunal) fruits. Speciation of small-fruited palms is particularly high in the understory of tropical rainforests in the New World, and on islands in the Old World. This suggests that frugivory-related traits in combination with geography and the movement behaviour of frugivores can influence the speciation of fleshy-fruited plants.

opencc-zeroAug 2019View details →

Data from: Demography-dispersal trait correlations modify the eco-evolutionary dynamics of range expansion

Spreading populations are subject to evolutionary processes acting on dispersal and reproduction that can increase invasion speed and variability. It is typically assumed that dispersal and demography traits evolve independently, but abundant evidence points to correlations between them that may be positive or negative, genetic or environmental. We sought to understand how demography-dispersal correlations modify the eco-evolutionary dynamics of range expansion. We first explored this question with the beetle Callosobruchus maculatus, a laboratory model in which evolutionary acceleration of invasion has been demonstrated. We then built a simulation model to explore the role of trait correlations in this system and more generally. We found that positive correlations amplify the positive influence of evolution on speed and variability, while negative correlations (such as we found empirically) constrain that influence. Strong negative genetic correlations can even cause evolution to decelerate invasion. Heritable and environmental correlations had similar effects on some measures of invasion but different effects on others. Model results enabled us to retrospectively explain invasion dynamics and trait evolution in C. maculatus, and may similarly aid the interpretation of other field and laboratory studies. Non-independence of demography and dispersal is an important consideration for understanding and predicting outcomes of range expansion.

opencc-zeroDec 2013View details →

Data from: Root community traits along a land use gradient: evidence of a community-level economics spectrum

1. There is a fundamental trade-off between leaf traits associated with either resource acquisition or resource conservation. This gradient of trait variation, called the economics spectrum also applies to fine roots but whether it is consistent for coarse roots or at the plant community level remains untested. 2. We measured a set of morphological and chemical root traits at a community level (functional parameters; FP) in 20 plant communities located along land-use intensity gradients and across 3 climatic zones (Tropical, Mediterranean and Montane). We hypothesized (i) the existence of a root economics spectrum in plant communities consistent within root types (fine, < 2 mm; coarse, 2-5 mm) but that ii) variations in root traits occur with soil depths (top 20 cm of soil and 100-150 cm deep) and iii) along land use gradients thus leading to variation in root FP. 3. Root FP co-varied, in line with the resource acquisition-conservation trade-off, from communities with root FP syndromes associated to resource acquisition (e.g. high specific root length, SRL; thin diameters and low root dry matter contents, RDMC) to root FP syndromes associated with resource conservation (e.g. low SRL, thick diameters and high RDMC). This pattern was consistent for both fine and coarse roots indicating a strong consistency of a trade-off between resource acquisition and conservation for plant roots. 4. Roots had different suites of traits at different depths, suggesting a disparity in root function and exploitation capacities. Shallow, fine roots were thinner, richer in nitrogen and with lower lignin concentrations associated to greater exploitation capacities compared to deep, fine roots. However, shallow coarse roots were richer in nitrogen, carbon and soluble concentrations than deep, coarse roots. 5. Fine root parameters of highly disturbed, herbaceous dominated plant communities in poorer soils were associated to foraging strategies, i.e. greater SRL and lower lignin and RDMC than those from less disturbed communities. Coarse roots however, were less sensitive to the land use gradient. 6. Synthesis This study demonstrates the existence of a general trade-off in root construction at a community level, which operates within all root types suggesting that all plant tissues are controlled by the trade-off between resource acquisition and conservation.

Data from: Effects of polyploidy and reproductive mode on life history trait expression

Ploidy elevation is increasingly recognized as a common and important source of genomic variation. Even so, the consequences and biological significance of polyploidy remain unclear, especially in animals. Here, our goal was to identify potential life history costs and benefits of polyploidy by conducting a large multiyear common garden experiment in Potamopyrgus antipodarum, a New Zealand freshwater snail that is a model system for the study of ploidy variation, sexual reproduction, host–parasite coevolution, and invasion ecology. Sexual diploid and asexual triploid and tetraploid P. antipodarum frequently coexist, allowing for powerful direct comparisons across ploidy levels and reproductive modes. Asexual reproduction and polyploidy are very often associated in animals, allowing us to also use these comparisons to address the maintenance of sex, itself one of the most important unresolved questions in evolutionary biology. Our study revealed that sexual diploid P. antipodarum grow and mature substantially more slowly than their asexual polyploid counterparts. We detected a strong negative correlation between the rate of growth and age at reproductive maturity, suggesting that the relatively early maturation of asexual polyploid P. antipodarum is driven by relatively rapid growth. The absence of evidence for life history differences between triploid and tetraploid asexuals indicates that ploidy elevation is unlikely to underlie the differences in trait values that we detected between sexual and asexual snails. Finally, we found that sexual P. antipodarum did not experience discernable phenotypic variance-related benefits of sex and were more likely to die before achieving reproductive maturity than the asexuals. Taken together, these results suggest that under benign conditions, polyploidy does not impose obvious life history costs in P. antipodarum and that sexual P. antipodarum persist despite substantial life history disadvantages relative to their asexual counterparts.

opencc-zeroDec 2014View details →

Data from: The tempo of trait divergence in geographic isolation: avian speciation across the Marañon valley of Peru

Geographic isolation is considered essential to most speciation events, but our understanding of what controls the pace and degree of phenotypic divergence among allopatric populations remains poor. Why do some taxa exhibit phenotypic differentiation across barriers to dispersal, whereas others do not? To test factors controlling phenotypic divergence in allopatry, we employed a comparative phylogeographic approach consisting of replicates of ecologically similar Andean bird species isolated across a major biogeographic barrier, the Marañon valley of Peru. Our study design leverages variation among co-distributed taxa in their degree of plumage, morphometric and vocal differentiation across the Marañon to examine the tempo of phenotypic evolution. We found that substantial plumage differences between populations required roughly two million years to evolve. In contrast, morphometric trait evolution showed greater idiosyncrasy and stasis. Our results demonstrate that despite a large degree of idiosyncrasy in the relationship between genetic and phenotypic divergence across taxa and environments, comparative studies within regions may reveal predictability in the pace of phenotypic divergence. Our results also suggest that social selection is important for driving differentiation of populations found in similar environments.

opencc-zeroDec 2018View details →

Data from: Seed and seedling traits have strong impacts on establishment of a perennial bunchgrass in invaded semi-arid systems

1. Many restoration projects use seeds to found new populations, and understanding phenotypic traits associated with seedling establishment in disturbed and invaded communities is important for restoration efforts worldwide. Focusing on the perennial grass Elymus elymoides, a native species common to sagebrush steppe communities in the Western United States, we asked if seed and seedling traits could predict field establishment. 2. We collected seeds from 34 populations from the western Great Basin. In greenhouse studies, we measured variation in seed and seedling characteristics of wild populations and one cultivar. We also quantified abiotic conditions at the collection location and asked if these characteristics predicted survival and other fitness metrics at five planting sites. Planting sites were all near-monocultures of the invasive annual grass Bromus tectorum, and all sites experienced similar, below-average precipitation during the experiment. 3. Phenotypic traits were strongly correlated with performance across all sites, with remarkably high predictive power. Seeds from populations with longer roots, larger seeds, and earlier emergence were significantly more likely to survive the first growing season (R2 = 0.66, P <0.0001). In contrast, while some abiotic variables at the collection location (e.g. 30 year average summer precipitation and fall minimum temperatures) were associated with field performance at some sites, abiotic variables explained less variation in performance than traits (average R2 = 0.22). Despite the low predictive power of abiotic variables, populations that performed best at each field site were from locations with climate variables similar to planting sites. 4. Synthesis and applications. The best seed sources for restoration of E. elymoides in invaded sites were populations with longer roots, larger seeds, and earlier emergence. These easily-measured traits were strong predictors of survival in disturbed field sites. While the most successful populations were found in areas with similar abiotic conditions as planting sites, there was phenotypic variation even among populations originating from locations with similar conditions. Thus, our results indicate that abiotic conditions are important considerations when selecting seeds, but these conditions may not sufficiently predict which populations will establish. Understanding population differences in seedling functional traits can improve predictions of restoration success.

opencc-zeroApr 2020View details →

Data from: True colors: commercially-acquired morphological genotypes reveal hidden allele variation among dog breeds, informing both trait ancestry and breed potential

Direct-to-consumer canine genetic testing is becoming increasingly popular among dog owners. The data collected therein provides intriguing insight into the current status of morphological variation present within purebred populations. Mars WISDOM PANELTM data from 11,790 anonymized dogs, representing 212 breeds and 4 wild canine species, were evaluated at genes associated with 7 coat color traits and 5 physical characteristics. Frequencies for all tested alleles at these 12 genes were determined by breed and by phylogenetic grouping. A sub-set of the data, consisting of 30 breeds, was divided into separate same-breed populations based on country of collection, body size, coat variation, or lineages selected for working or conformation traits. Significantly different (p ≤ 0.00167) allele frequencies were observed between populations for at least one of the tested genes in 26 of the 30 breeds. Next, standard breed descriptions from major American and international registries were used to determine colors and tail lengths (e.g. genetic bobtail) accepted within each breed. Alleles capable of producing traits incongruous with breed descriptions were observed in 143 breeds, such that random mating within breeds has probabilities of between 4.9e-7 and 0.25 of creating undesirable phenotypes. Finally, the presence of rare alleles within breeds, such as those for the recessive black coloration and natural bobtail, was combined with previously published identity-by-decent haplotype sharing levels to propose pathways by which the alleles may have spread throughout dog breeds. Taken together, this work demonstrates that: 1) the occurrence of low frequency alleles within breeds can reveal the influence of regional or functional selection practices; 2) it is possible to trace the mode by which characteristics have spread across breeds during historical breed formation; and 3) the necessity of addressing conflicting ideals in breed descriptions relative to actual genetic potential is crucial.

Data from: Functional traits for carbon access in macrophytes

Understanding functional trait distributions among organisms can inform impacts on and responses to environmental change. In marine systems, only 1% of dissolved inorganic carbon in seawater exists as CO2. Thus the majority of marine macrophytes not only passively access CO2 for photosynthesis, but also actively transport CO2 and the more common bicarbonate (HCO3-, 92% of seawater dissolved inorganic carbon) into their cells. Because species with these carbon concentrating mechanisms (CCMs) are non-randomly distributed in ecosystems, we ask whether there is a phylogenetic pattern to the distribution of CCMs among algal species. To determine macrophyte traits that influence carbon uptake, we assessed 40 common macrophyte species from the rocky intertidal community of the Northeast Pacific Ocean to a) query whether macrophytes have a CCM and b) determine the evolutionary history of CCMs, using ancestral state reconstructions and stochastic character mapping based on previously published data. Thirty-two species not only depleted CO2, but also concentrated and depleted HCO3-, indicative of a CCM. While analysis of CCMs as a continuous trait in 30 families within Phylum Rhodophyta showed a significant phylogenetic signal under a Brownian motion model, analysis of CCMs as a discrete trait (presence or absence) indicated that red algal families are more divergent than expected in their CCM presence or absence; CCMs are a labile trait within the Rhodophyta. In contrast, CCMs were present in each of 18 Ochrophyta families surveyed, indicating that CCMs are highly conserved in the brown algae. The trait of CCM presence or absence was largely conserved within Families. Fifteen of 23 species tested also changed the seawater buffering capacity, or Total Alkalinity (TA), shifting DIC composition towards increasing concentrations of HCO3- and CO2 for photosynthesis. Manipulating the external TA of the local environment may influence carbon availability in boundary layers and areas of low water mixing, offering an additional mechanism to increase CO2 availability.

opencc-zeroDec 2014View details →

Data from: Natural variation, differentiation and genetic tradeoffs of ecophysiological traits in response to water limitation in Brachypodium distachyon and its descendent allotetraploid B. hybridum (Poaceae)

Differences in tolerance to water stress may underlie ecological divergence of closely-related ploidy lineages. However, the mechanistic basis of physiological variation governing eco-geographical cytotype segregation is not well understood. Here, using Brachypodium distachyon and its derived allotetraploid B. hybridum as model, we test the hypothesis that, for heteroploid annuals, ecological divergence of polyploids in drier environments is based on trait differentiation enabling drought-escape. We demonstrate that under water limitation allotetraploids maintain higher photosynthesis and stomatal conductance and show earlier flowering than diploids, concordant with a drought-escape strategy to cope with water stress. Increased heterozygosity, greater genetic variability and plasticity of polyploids could confer a superior adaptive capability. Consistent with these predictions, we document (1) greater standing within-population genetic variation in water use efficiency and flowering time in allotetraploids, and (2) the existence of (non-linear) environmental clines in physiology across allotetraploid populations. Increased gas exchange and diminished WUE occurred at the driest end of the gradient, consistent with a drought-escape strategy. Finally, we found that allotetraploids showed weaker genetic correlations than diploids congruous with the expectation of relaxed pleiotropic constraints in polyploids. Our results suggest evolutionary divergence of ecophysiological traits in each ploidy lineage.

Data from: Which traits do observers use to distinguish Batesian mimics from their models?

Batesian mimicry, in which a harmless mimic resembles a more aversive model, can encompass a wide range of morphological traits, but the resemblance is never perfect. Previous studies have used abstract "prey" designs to show that differences in certain traits may not be relevant to mimicry if they are not perceived or recognized by a predator. Here, we extend these results by examining how human "predators" respond to realistic variation in traits of aposematic wasps and their hoverfly mimics. We measured the ability of humans to discriminate between images of wasps and hoverflies in which only certain traits were visible, to determine the contributions of those traits to discrimination decisions. We found that shape is a particularly useful and easily learnt trait for separating the 2 taxa. Subjects did not successfully discriminate on the basis of abdominal patterns, despite those containing useful information. Color similarity between wasps and hoverflies is relatively high in comparison with other traits, suggesting that selection has acted more strongly on color. Our findings demonstrate the importance of consideration of natural variation in the traits of prey and their salience to predators for understanding the evolution of prey defenses.

opencc-zeroJun 2019View details →

Data from: Evolution of asexual Daphnia pulex in Japan: variations and covariations of the digestive, morphological and life history traits

Background Several genetic lineages of obligate parthenogenetic Daphnia pulex, a common zooplankton species, have invaded Japan from North America. Among these, a lineage named JPN1 is thought to have started colonization from a single genotype several hundred to thousand years ago and subsequently produced many genotypes in Japan. To examine the phenotypic variations due to ecological drivers diverging the genotypes in new habitats, we measured heritability and variation in 17 traits, including life history, morphology and digestive traits, and the genetic distance among the D. pulex JPN1 genotypes in Japan. Results We found that most of the traits measured varied significantly among the genotypes and that heritability was highest in the morphological traits, followed by the digestive and life history traits. In addition, 93% of the variation in these traits was explained by the first three components in the principal component analysis, implying that variations of these heritable traits are not random but rather converged into a few directions. These relations among traits revealed the potential importance of predation pressures and food conditions as factors for diverging and selecting different genotypes. However, the magnitude of the difference in any single trait group did not correlate with the genetic distance. Conclusions Our findings show that the divergent traits evolved within D. pulex JPN1 without genetic recombination since their ancestral clone invaded Japan. Large variations and covariations of the phenotypic traits, irrespective of the genetic distance among the genotypes, support the view that the invasive success of D. pulex JPN1 was promoted by a genetic architecture that allowed for large phenotypic variations with a limited number of functionally important mutations without recombination.

opencc-zeroDec 2013View details →

Data from: The interplay between local ecology, divergent selection and genetic drift in population divergence of a sexually antagonistic female trait

Genetically polymorphic species offer the possibility to study maintenance of genetic variation and the potential role for genetic drift in population divergence. Indirect inference of the selection regimes operating on polymorphic traits can be achieved by comparing population divergence in neutral genetic markers with population divergence in trait frequencies. Such an approach could further be combined with ecological data to better understand agents of selection. Here, we infer the selective regimes acting on a polymorphic mating trait in an insect group; the dorsal structures (either rough or smooth) of female diving beetles. Our recent work suggests that the rough structures have a sexually antagonistic function in reducing male mating attempts. For two species (Dytiscus lapponicus and Graphoderus zonatus), we could not reject genetic drift as an explanation for population divergence in morph frequencies, while for the third (Hygrotus impressopunctatus) we found that divergent selection pulls morph frequencies apart across populations. Furthermore, population morph frequencies in H. impressopunctatus were significantly related to local bioclimatic factors, providing an additional line of evidence for local adaptation in this species. These data therefore suggest that local ecological factors and sexual conflict interact over larger spatial scales to shape population divergence in the polymorphism.

opencc-zeroDec 2012View details →

Data from: The quantitative genetics of physiological and morphological traits in an invasive terrestrial snail: additive versus non-additive genetic variation

1. The distribution of additive versus non-additive genetic variation in natural populations represents a central topic of research in evolutionary/organismal biology. For evolutionary physiologists, functional or whole-animal performance traits ("physiological traits") are frequently studied assuming they are heritable and variable in populations. 2. Physiological traits of evolutionary relevance are those functional capacities measured at the whole-organism level, with a potential impact on fitness. They can be classified as capacities (or performances) or costs, the former being directly correlated with fitness, and the latter being inversely correlated with fitness (usually assumed as constraints). 3. In spite of their obvious adaptive significance, the additive genetic variation of physiological traits, and its relative contribution to phenotypic variance (or narrow-sense heritability) in comparison to maternal, dominance or epistatic variance, is known only for a few groups such as insects and mammals. 4. In this study, we assessed the additive and maternal/non-additive genetic variation in a suite of physiological and morphological traits in populations of the land snail Cornu aspersum. 5.Except for dehydration rate (h2= 0.32 ± 0.15), egg mass (h2= 0.82 ± 0.30) and hatchling mass (h2= 1.01 ± 0.31) (population = fixed effect), we found very low additive genetic variation. Large non-additive/maternal effects were found in all traits. Cage effects did not change the results, indicating low contribution of common environmental variance to our results. No differences were found between the phenotypic or non-additive genetic variance/covariance matrices. 6. Even though we compared populations across 1300 km in a common garden setup, our results suggest an absence of physiological as well as morphological differentiation in these populations. 7. These results contrast with previous analyses in the original distributional range of this species, which found high additive genetic variation in morphological traits. These are intriguing results demanding further quantitative genetic studies in the original distributional range of this species as well as the history of colonization of this invasive species.

Data from: Predation shapes the evolutionary traits of cervid weapons

Sexually selected weapons evolved to maximize the individual reproductive success of males in many polygynous breeding species. Many weapons are also retained outside of reproductive periods for secondary reasons, but the importance of these secondary functions is poorly understood. Here we leveraged a unique opportunity from the predator–prey system in northern Yellowstone National Park, WY, USA to evaluate whether predation by a widespread, coursing predator (wolves) has influenced a specific weapon trait (antler retention time) in their primary cervid prey (elk). Male elk face a trade-off: individuals casting antlers early begin regrowth before other males, resulting in relatively larger antlers the following year, and thus greater reproductive success, as indicated by research with red deer. We show, however, that male elk that cast their antlers early are preferentially hunted and killed by wolves, despite early casters being in better nutritional condition than antlered individuals. Our results run counter to classic expectations of coursing predators preferring poorer-conditioned individuals, and in so doing, reveal an important secondary function for an exaggerated sexually selected weapon—predatory deterrence. We suggest this secondary function played a key evolutionary role in elk; uniquely among North American cervids, they retain their antlers long after they fulfil their primary role in reproduction.